fix: make esbuild work with ESM and require calls (#1257)

.eslintrc.cjs

@@ -9,6 +9,7 @@ module.exports = {
     'import/extensions': ['error', 'ignorePackages'],
     'n/no-missing-import': 'off',
     'no-magic-numbers': 'off',
+    'max-lines-per-function': 'off',
     // This rule enforces using Buffers with `JSON.parse()`. However, TypeScript
     // does not recognize yet that `JSON.parse()` accepts Buffers as argument.
     'unicorn/prefer-json-parse-buffer': 'off',

src/feature_flags.ts

@@ -20,6 +20,9 @@ export const defaultFlags: Record<string, boolean> = {
 
   // Load configuration from per-function JSON files.
   project_deploy_configuration_api_use_per_function_configuration_files: false,
+
+  // Provide banner to esbuild which allows requires in ESM output
+  zisi_esbuild_require_banner: false,
 }
 
 export type FeatureFlag = keyof typeof defaultFlags

src/runtimes/node/bundlers/esbuild/bundler.ts

@@ -108,8 +108,21 @@ export const bundleJsFile = async function ({
   const outExtension =
     moduleFormat === ModuleFormat.ESM ? { [ModuleFileExtension.JS]: ModuleFileExtension.MJS } : undefined
 
+  // We add this banner so that calls to require() still work in ESM modules, especially when importing node built-ins
+  // We have to do this until this is fixed in esbuild: https://github.com/evanw/esbuild/pull/2067
+  const esmJSBanner = `
+    import {createRequire as ___nfyCreateRequire} from "module";
+    import {fileURLToPath as ___nfyFileURLToPath} from "url";
+    import {dirname as ___nfyPathDirname} from "path";
+    let __filename=___nfyFileURLToPath(import.meta.url);
+    let __dirname=___nfyPathDirname(___nfyFileURLToPath(import.meta.url));
+    let require=___nfyCreateRequire(import.meta.url);
+  `
+
   try {
     const { metafile = { inputs: {}, outputs: {} }, warnings } = await build({
+      banner:
+        moduleFormat === ModuleFormat.ESM && featureFlags.zisi_esbuild_require_banner ? { js: esmJSBanner } : undefined,
       bundle: true,
       entryPoints: [srcFile],
       external,

tests/fixtures/node-require-in-esm/functions/func1.mjs

@@ -0,0 +1,3 @@
+import include from '../include.cjs';
+
+export const handler = () => true

tests/fixtures/node-require-in-esm/include.cjs

@@ -0,0 +1,3 @@
+const path = require('path');
+
+export default 1

tests/main.test.ts

@@ -14,9 +14,10 @@ import unixify from 'unixify'
 import { afterAll, afterEach, describe, expect, test, vi } from 'vitest'
 
 import type { Config } from '../src/config.js'
-import { NodeBundlerType } from '../src/main.js'
 import { ESBUILD_LOG_LIMIT } from '../src/runtimes/node/bundlers/esbuild/bundler.js'
+import { NodeBundlerType } from '../src/runtimes/node/bundlers/types.js'
 import { detectEsModule } from '../src/runtimes/node/utils/detect_es_module.js'
+import { ModuleFormat } from '../src/runtimes/node/utils/module_format.js'
 import { shellUtils } from '../src/utils/shell.js'
 
 import {
@@ -2418,4 +2419,34 @@ describe('zip-it-and-ship-it', () => {
       }
     },
   )
+
+  test('Provides require to esbuild if output format is ESM', async () => {
+    const fixtureName = 'node-require-in-esm'
+    const opts = {
+      basePath: join(FIXTURES_DIR, fixtureName),
+      config: {
+        '*': {
+          nodeBundler: NodeBundlerType.ESBUILD,
+          nodeModuleFormat: ModuleFormat.ESM,
+        },
+      },
+      featureFlags: {
+        zisi_esbuild_require_banner: true,
+      },
+    }
+    const { files, tmpDir } = await zipFixture([join(fixtureName, 'functions')], {
+      opts,
+    })
+
+    await unzipFiles(files, (path) => `${path}/../${basename(path)}_out`)
+
+    const funcFile = join(tmpDir, `func1.zip_out/func1.mjs`)
+
+    // We have to use execa because when we simply import the file here vitest does provide a `require` function
+    // and therefore we do not trigger the problem
+    const result = await execa.node(funcFile, [], { extendEnv: false, reject: false })
+
+    expect(result.stderr).not.toContain('Dynamic require of "path" is not supported')
+    expect(result).not.toBeInstanceOf(Error)
+  })
 })